package com.albertyjz.juc;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;

class MyTask extends RecursiveTask<Integer>{
    private static final Integer ADJUST_VALUE=10;
    private int begin;
    private int end;
    private int result;

    public MyTask(int begin, int end) {
        this.begin = begin;
        this.end = end;
    }

    @Override
    protected Integer compute() {
        if((end-begin)<=ADJUST_VALUE){
            for(int i=begin;i<=end;i++){
                result=result+i;
            }
        }else{
            int middle=(end+begin)/2;
            MyTask task01=new MyTask(begin,middle);
            MyTask task02=new MyTask(middle+1,end);
            //递归，调fork就是调用compute
            task01.fork();
            task02.fork();
            result=task01.join()+task02.join();
        }
        return result;
    }
}

public class ForkJoin {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        MyTask myTask=new MyTask(0,100);
        ForkJoinPool threadPool=new ForkJoinPool();
        ForkJoinTask<Integer> forkJoinTask=threadPool.submit(myTask);
        System.out.println(forkJoinTask.get());
        threadPool.shutdown();
    }
}
